just months before the bombings, tamerlan tsarnaev shop here at this fireworks store in new hampshire. the store owner said he purchased these large lock and load mortar kits. 48 fireworks in all. what was his demeanor when he bought this? >> just a normal everyday customer. he wasn't overly friendly or rude. >> reporter: from his hospital bed, bombing suspect dzhokhar is filling in the blanks saying they learned how to make a bomb from the internet. dzhokhar told investigators he and his brother acted alone and offered a motive, too. the brothers believe the u.s. wars in iraq and afghanistan were an attack on islam. the day after the boston attack, dzhokhar spoke with college friends at the gym. >> i talked to him about how it was crazy that we had a bombing in boston. >> you said that, you talked about the bombing? >> yes, i said it's a real tragedy that it's happened in afghanistan and around the world. >> reporter: meanwhile, tamerlan's wife katie lives in seclusion at her parents' home in rhode island. >> the reports of violence by her husband and brother-in-law came as an absolu